1. Field of the Invention
The present invention relates to apparatus and an associated method for making a gas conduit coupling structure for a pressurized gas conduit and, more specifically, for making a conduit coupling structure which does not require welded parts.
2. Background Information
Conduits are well known in the prior art. Conduits may be employed for a variety of purposes, such as for encasing and supporting electrical conductors and for the transporting or channeling of fluids. A variety of methods are employed to produce such conduits. Such methods include metal extrusion, wherein metal is extruded through an extrusion die to form the conduit, and metal casting, wherein metal is cast in a mold to form the conduit.
One particularly advantageous way of forming conduit is by forming already corrugated sheet metal, such as stainless steel which may be 304 stainless steel, into a tubular shape and welding the seam which is formed where the sides of the sheet metal meet. Another particularly advantageous way of forming conduit is to form generally flat, sheet metal, such as 304 stainless steel, into a tubular shape, weld the seam which is formed where the sides of the sheet metal meet and then corrugate the tube. Such corrugated tubing is useful in a variety of applications. Also, non-corrugated conduit, such as copper tubing, may be employed in certain applications.
Frequently, when gas conduit is run through a building, the conduit must change its direction of path a number of times. One way to allow for such directional change is through the employment of elbow-type fittings or connectors. The employment of such elbow-type devices is, sometimes, undesirable since the fittings or connectors are relatively expensive and increase the risk of leaks when the conduits are employed for the purpose of containing a fluid such as a gas or liquid, since a positive seal between the conduit and the fitting may not always be achieved. Another method of changing the direction of conduit is, simply, by bending the conduit at the desired locations of changes of direction of the path of the conduit.
Devices for properly bending non-corrugated conduit are well known. However, if the bending devices are not used properly, or if the conduit is simply bent without the employment of such bending devices, the conduit may bend at too small of a radius of curvature, thereby forming what is generally known as a "kink." A kink may narrow the inside diameter of the conduit to such an extent that fluid flow, therethrough, is restricted or possibly even stopped. A kink may be so severe that a hole may even form in the wall of the conduit, thereby allowing escape of the fluid from the conduit.
One advantage of using non-corrugated conduit is that end fittings have been developed, such as standard, well known compression type fittings, to provide a simplified means of connecting the tubing to another section of tubing or some other device such as a connector. Therefore, while the employment of non-corrugated conduit provides an advantage in the simplified connection of the conduit to another device, it has the disadvantage of being difficult to change the direction of the path of the conduit, as described above.
Corrugated conduit, on the other hand, may be easily bent for changes in direction of path, with little risk of kinking, because the corrugated configuration significantly reduces the risk of kinking. However, due to the corrugated, or rippled, surface of the conduit, standard compression fittings have not, heretofore, been effective for providing a fluid tight seal between the ends of the conduit and another piece of conduit or a connector. The ineffectiveness of the seal is due to the fact that such compression fittings rely, in part, on a conduit which has a relatively smooth, exterior end surface, such as is present in copper tubing, to provide the necessary seal. Therefore, typical corrugated conduit requires fittings which must be welded to the conduit to provide an effective seal. Such welding, however, is inconvenient and relatively expensive.
Thus, the advantages and disadvantages encountered when using corrugated conduit are opposite the advantages and disadvantages provided by copper tubing since corrugated conduit is easily bent but difficult to easily connect to other devices while the copper tubing is relatively difficult to bend but provides easy connection to other devices.
Therefore, a need exists to provide a conduit for fluids or gas which is both easy to bend and easy to connect to other devices. The present invention has fulfilled this need.